Glass for optical amplifier fiber

Abstract

A germanate glass composition suitable for use in a fiber amplifier for broadband amplification of optical signals is provided. The glass preferably includes 35-75% GeO 2 , 0-45% PbO, 5-20% BaO, 5-20% ZnO, and 2-10% R 2 O (R=Na, Li, K). It is doped with thulium ions (Tm 3+ ) and codoped with holmium ions (Ho 3+ ). The glass composition of results in a remarkably large bandwidth as compared with previous glasses. It is also highly compatible with existing silica optical fibers.

1. A germanate glass composition for optical fiber amplification being doped with Tm 3+  and Ho 3+  and further comprising at least 35 mole % GeO 2  and oxides of Ba, Zn and R, R being selected from the group of Na, Li, and K, said glass composition comprising:
 about 50 mole % GeO 2 ; 
 about 25 mole % PbO; 
 about 10 mole % BaO; 
 about 10 mole % ZnO; and 
 about 5 mole % R 2 O 
 
     for broadening the amplification wavelength band associated with the glass composition. 
   
   
     2. The glass composition according to  claim 1 , wherein the glass component amounts are such that the amplification wavelength band is at least 250 nm. 
   
   
     3. The glass composition according to  claim 1 , wherein R is K. 
   
   
     4. The glass composition according to  claim 1 , comprising 0.01-2.5 mole % Tm 3+  and 0.01-2.5 mole % Ho 3+ . 
   
   
     5. An optical amplifier fiber comprising a core surrounded by at least one cladding ( 14 ), wherein the core is at least partly formed of a germanate glass composition doped with Tm 3+  and Ho 3+  and further comprising at least 35 mole % GeO 2  and oxides of Ba, Zn and R, R being selected from the group of Na, Li, and K, said glass composition comprising:
 about 50 mole % GeO 2 ; 
 about 25 mole % PbO; 
 about 10 mole % BaO; 
 about 10 mole % ZnO; and 
 about 5 mole % R 2 O 
 
     for broadening the amplification wavelength band of the optical amplifier fiber. 
   
   
     6. The amplifier fiber according to  claim 5 , wherein the glass component amounts are such that the amplification wavelength band is at least 250 nm. 
   
   
     7. The amplifier fiber according to  claim 5 , wherein R is K. 
   
   
     8. The amplifier fiber according to  claim 5 , wherein the glass composition comprises 0.01-2.5 mole % Tm 3+  and 0.01-2.5 mole % Ho 3+ . 
   
   
     9. An optical amplifier including an optical amplifier fiber comprising a core surrounded by at least one cladding, wherein the core is at least partly formed of a germanate glass composition doped with Tm 3+  and Ho 3+  and further comprising at least 35 mole % GeO 2  and oxides of Ba, Zn and R, R being selected from the group of Na, Li, and K, said glass composition comprising:
 about 50 mole % GeO 2 ; 
 about 25 mole % PbO; 
 about 10 mole % BaO; 
 about 10 mole % ZnO; and 
 about 5 mole % R 2 O 
 
     for broadening the amplification wavelength band of the optical amplifier fiber. 
   
   
     10. The optical amplifier according to  claim 9 , forming a complementary amplifier for side-band amplification. 
   
   
     11. A laser device ( 30 ) including an optical amplifier fiber, wherein the optical amplifier fiber is at least partly formed of a germanate glass composition doped with Tm 3+  and Ho 3+  and further comprising at least 35 mole % GeO 2  and oxides of Ba, Zn and R, R being selected from the group of Na, Li, and K, said glass composition comprising:
 about 50 mole % GeO 2 ; 
 about 25 mole % PbO; 
 about 10 mole % BaO; 
 about 10 mole % ZnO; and 
 about 5 mole % R 2 O 
 
     for broadening the amplification wavelength band of the optical amplifier fiber.